A semiconductor is manufactured through steps of fabricating a wafer, injecting predetermined ions into such a wafer, forming a circuit pattern, and the like. At this point, in order to fabricate the wafer, a single crystal silicon should be grown in an ingot form. For this, the Czochralski (CZ) method may be applied.
Currently, a quartz crucible is used to accommodate silicon melt, which is melted in a method for fabricating a single crystal ingot by the CZ method. Such a quartz crucible is converted into SiOx by being dissolved in the melt accompanied by reaction with the silicon melt. The SiOx is mixed into the ingot and forms bulk micro defects (BMD) or the like, which acts as a gathering site for metal impurities during a semiconductor process or causes various defects and segregation, which may adversely affect yield of the semiconductor device.
In order to control an oxygen concentration in such a single crystal ingot, there is a method for largely changing a hot zone (H/Z) in a crystal growth furnace in advance. For example, there has been widely discussed on a method for controlling a dissolution rate of the quartz crucible by adjusting a length of a heater, adjusting a slit or the like.
In addition, there is a method for controlling the oxygen concentration by adjusting a rotational speed of the single crystal ingot, a rotational speed of the quartz crucible, and argon or pressure in the growth furnace.
Further, there is another method for controlling the oxygen concentration through melt convection using a magnetic field.
Japanese Patent Application No. 2008-214118 discloses a method for controlling an oxygen concentration in a longitudinal direction of a silicon single crystal in which a correlation between a magnetic field center position and an oxygen concentration is obtained and a single crystal is pulled up while controlling the magnetic field center position.
However, according to the related art, when the magnetic field center position moves to a silicon melt interface, the oxygen concentration is largely changed by forming a convection pattern in which a flow of the melt is complicated, and thus there is a problem that the oxygen concentration is not uniform in a radial direction of the single crystal ingot.